Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – C1

ANSWER — 

Correct.

The tracings reveal a repeated pattern of sustained very low glucose values in the early hours of the morning while the patient is asleep (figure 1). On one occasion, the blood glucose level was <40 mg/dL (2.2 mmol/L) for approximately five hours. The low nocturnal glucose values are preceded by bedtime glucose values that are not low and followed by fasting glucose values that are not low, so that glucose monitoring at the usual times would not have suggested (and did not suggest) the occurrence of nocturnal hypoglycemia during the study. There is a marked rise in the glucose values between breakfast and lunch not related to the contents of the breakfasts, with peak glucose values of >300 mg/dL (16.6 mmol/L) in the mid-morning. The peak glucose values in mid-morning are higher than the values before lunch.

The findings demonstrate the high probability of undetected hypoglycemia when glycated hemoglobin (A1C) levels are normal or nearly normal and fingerstick blood glucose levels are elevated. In this setting, there must be many low glucose values, whether or not they are detected, to offset the measured high glucose values (assuming that a hemoglobinopathy or recent blood transfusions does not account for the discordance between the hyperglycemia on fingerstick blood glucose values and the A1C level).

What is your assessment and plan?

●You conclude that the patient is having nocturnal hypoglycemia after all. You also decide that she is on too much NPH insulin at bedtime. You reduce the NPH at bedtime to 7 units and advise the patient to increase the prandial dose of lispro before breakfast by 3 units, in addition to the 1 unit for 12 grams of carbohydrate she has been using. (See "Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – D1".)

●You conclude that the patient is having nocturnal hypoglycemia after all. You also decide that the use of NPH insulin at bedtime is not effective, because it is not a true basal insulin but peaks at night during the hours of sleep. You advise the patient to change the basal insulin from NPH twice daily to insulin glargine 16 units at bedtime. (See "Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – D2".)

●You conclude that the patient is having nocturnal hypoglycemia after all. You decide that even small doses of NPH at bedtime are excessive and advise the patient to stop the bedtime NPH insulin. (See "Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – D3".)